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Module: ActiveRecord::ConnectionAdapters::QueryCache

Relationships & Source Files
Namespace Children
Modules:
ConnectionPoolConfiguration
Classes:
Store
Defined in: activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb

Constant Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Class Method Details

.dirties_query_cache(base, *method_names)

[ GitHub ] 

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 19



def dirties_query_cache(base, *method_names)
  method_names.each do |method_name|
    base.class_eval <<-end_code, __FILE__, __LINE__ + 1
      def #{method_name}(...)
        if pool.dirties_query_cache
          ActiveRecord::Base.clear_query_caches_for_current_thread
        end
        super
      end
    end_code
  end
end


  








  

    .included(base)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 11



def included(base) # :nodoc:
  dirties_query_cache base, :exec_query, :execute, :create, :insert, :update, :delete, :truncate,
    :truncate_tables, :rollback_to_savepoint, :rollback_db_transaction, :restart_db_transaction,
    :exec_insert_all

  base.set_callback :checkin, :after, :unset_query_cache!
end


  







Instance Attribute Details



  

    #query_cache   (rw)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 165



attr_accessor :query_cache


  







Instance Method Details



  

    #cache(&block)  
  



  

    

Enable the query cache within the block.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 177



def cache(&block)
  pool.enable_query_cache(&block)
end


  








  

    #cache_notification_info(sql, name, binds)   (private)
  



  

    

Database adapters can override this method to provide custom cache information.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 273



def cache_notification_info(sql, name, binds)
  {
    sql: sql,
    binds: binds,
    type_casted_binds: -> { type_casted_binds(binds) },
    name: name,
    connection: self,
    cached: true
  }
end


  








  

    #cache_sql(sql, name, binds)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 249



def cache_sql(sql, name, binds)
  key = binds.empty? ? sql : [sql, binds]
  result = nil
  hit = true

  @lock.synchronize do
    result = @query_cache.compute_if_absent(key) do
      hit = false
      yield
    end
  end

  if hit
    ActiveSupport::Notifications.instrument(
      "sql.active_record",
      cache_notification_info(sql, name, binds)
    )
  end

  result.dup
end


  








  

    #clear_query_cache  
  



  

    

Clears the query cache.



One reason you may wish to call this method explicitly is between queries that ask the database to randomize results. Otherwise the cache would see the same SQL query and repeatedly return the same result each time, silently undermining the randomness you were expecting.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 203



def clear_query_cache
  pool.clear_query_cache
end


  








  

    #disable_query_cache!  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 193



def disable_query_cache!
  pool.disable_query_cache!
end


  








  

    #enable_query_cache!  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 181



def enable_query_cache!
  pool.enable_query_cache!
end


  








  

    #initialize  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 167



def initialize(*)
  super
  @query_cache = nil
end


  








  

    #lookup_sql_cache(sql, name, binds)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 231



def lookup_sql_cache(sql, name, binds)
  key = binds.empty? ? sql : [sql, binds]

  result = nil
  @lock.synchronize do
    result = @query_cache[key]
  end

  if result
    ActiveSupport::Notifications.instrument(
      "sql.active_record",
      cache_notification_info(sql, name, binds)
    )
  end

  result
end


  








  

    #query_cache_enabled  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 172



def query_cache_enabled
  @query_cache&.enabled?
end


  








  

    #select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 207



def select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false) # :nodoc:
  arel = arel_from_relation(arel)

  # If arel is locked this is a SELECT ... FOR UPDATE or somesuch.
  # Such queries should not be cached.
  if @query_cache&.enabled? && !(arel.respond_to?(:locked) && arel.locked)
    sql, binds, preparable, allow_retry = to_sql_and_binds(arel, binds, preparable)

    if async
      result = lookup_sql_cache(sql, name, binds) || super(sql, name, binds, preparable: preparable, async: async, allow_retry: allow_retry)
      FutureResult.wrap(result)
    else
      cache_sql(sql, name, binds) { super(sql, name, binds, preparable: preparable, async: async, allow_retry: allow_retry) }
    end
  else
    super
  end
end


  








  

    #uncached(dirties: true, &block)  
  



  

    

Disable the query cache within the block.



Set dirties: false to prevent query caches on all connections from being cleared by write operations. (By default, write operations dirty all connections’ query caches in case they are replicas whose cache would now be outdated.)


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 189



def uncached(dirties: true, &block)
  pool.disable_query_cache(dirties: dirties, &block)
end


  








  

    #unset_query_cache!   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 227



def unset_query_cache!
  @query_cache = nil
end